The present invention relates to the method of quantifying protective ratio of the hydroxyl groups of a polymer compound.
A polymer compound composed of the following first structural unit and second structural unit is useful, for example, as a resin component of a photoresist:
first structural unit: a structural unit with a structure having a hydroxyl group,
second structural unit: a structural unit with a structure obtained by introducing a protective group into the hydroxyl group in the first structural unit.
In such a polymer compound, the protective ratio of the hydroxyl groups showing content ratio of the first structural unit to the second structural unit is important. As a highly precise quantitative method such a protective ratio, quantitative methods according to an NMR method are known in which quantification is effected from a nuclear magnetic resonance (NMR) spectrum of a polymer compound (JP-A Nos. 5-249682, 8-123032, 10-147614 and the like).
However, the quantitative method according to an NMR method has a problem that measurement of an NMR spectrum requires a comparatively longer period of time. Further, when the polymer compounds are contained together with foreign materials in the measuring sample, the NMR spectrum is need to be measured, after a previous treatment of isolating the polymer compound from the sample mixture.
As a quantitative method that can quantify the protective ratio of the hydroxyl groups of the polymer compound In a short period (of time) without isolating a polymer compound from the sample mixtures the quantitative method according to a thermal decomposition gas chromatograph method is exemplified, in which the sample is thermally decomposed and the yielded fragments are measured by a gas chromatography. This method, however, is not a precise quantitative method since the polymer compound is thermally decomposed for quantification.
The present inventors have intensively studied to develop a quantitative method which can quantify the protective ratio of the hydroxyl groups of the polymer compound at high precision in a short period of time without isolating the polymer compound from the measuring sample, and resultantly found that the protective ratio of the hydroxyl groups of the polymer compound contained in the sample can be quantified at high precision in a short period of time even if the sample contains foreign materials, by calculating the protective ratio from the near infrared absorption spectrum of the sample containing the polymer compound using a multiple regression calibration curve obtained by analyzing the main components of the near infrared absorption spectra of a plurality of standard samples. Thus, the present invention was completed.
The present invention provides a method of quantifying the protective ratio of the hydroxyl groups of the polymer compound, comprising calculating the protective ratio of the hydroxyl groups of the polymer compound using a multiple regression calibration curve obtained by regression-analyzing the main components of the near infrared absorption spectra of a plurality of standards samples, from the near infrared absorption spectra of samples containing the polymer compound composed of the following first structural unit and second structural unit:
first structural unit: a structural unit of the structure having a hydroxyl group,
second structural unit: a structural unit of the structure obtained by Introducing a protecting group into a hydroxyl group in the first structural unit.